WeldApplication.java

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2008, Red Hat Middleware LLC, and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jboss.weld.environment.servlet.jsf;

import javax.el.ELResolver;
import javax.el.ExpressionFactory;
import javax.enterprise.inject.spi.BeanManager;
import javax.faces.application.Application;
import javax.faces.context.FacesContext;
import javax.servlet.ServletContext;

import org.jboss.weld.environment.servlet.util.AbstractForwardingELResolver;
import org.jboss.weld.environment.servlet.util.TransparentELResolver;

/**
 * @author Pete Muir
 * @author Dan Allen
 * @author Ales Justin
 */
public class WeldApplication extends AbstractForwardingApplication {

    /**
     * The BeanManager may not have been initialized at the time JSF is initializing. Therefore, we
     * stick in a ForwardingELResolver that delegates to the BeanManager ELResolver, which will be
     * plugged in when it's available. If the ELResolver is invoked before the BeanManager is
     * available, the resolver will perform no action (and thus produce no result).
     */
    private static class LazyBeanManagerIntegrationELResolver extends AbstractForwardingELResolver {

        private ELResolver delegateResolver;

        public LazyBeanManagerIntegrationELResolver() {
            delegateResolver = new TransparentELResolver();
        }

        public void beanManagerReady(BeanManager beanManager) {
            delegateResolver = beanManager.getELResolver();
        }

        @Override
        protected ELResolver delegate() {
            return delegateResolver;
        }
    }

    private final Application application;
    private LazyBeanManagerIntegrationELResolver elResolver;
    private ExpressionFactory expressionFactory;
    private BeanManager beanManager;

    public WeldApplication(Application application) {
        this.application = application;
        // QUESTION should the context listener be registered in init() instead?
        application.addELContextListener(new org.jboss.weld.el.WeldELContextListener());
        elResolver = new LazyBeanManagerIntegrationELResolver();
        application.addELResolver(elResolver);
    }

    private void init() {
        ExpressionFactory factory = application.getExpressionFactory();
        BeanManager beanManager = getBeanManager();
        if (factory != null && beanManager != null) {
            elResolver.beanManagerReady(beanManager);
            this.expressionFactory = beanManager.wrapExpressionFactory(factory);
        }
    }

    @Override
    protected Application delegate() {
        init();
        return application;
    }

    @Override
    public ExpressionFactory getExpressionFactory() {
        init();
        if (expressionFactory == null) {
            return application.getExpressionFactory();
        }
        else {
            return expressionFactory;
        }
    }

    private BeanManager getBeanManager() {

        if (beanManager == null) {
            FacesContext facesContext = FacesContext.getCurrentInstance();
            if (facesContext != null) {
                return lookupBeanManager(facesContext);
            }
        }
        return beanManager;
    }

    private BeanManager lookupBeanManager(FacesContext facesContext) {
        Object obj = facesContext.getExternalContext().getContext();
        boolean notFound = false;
        try {
            if (obj instanceof ServletContext) {
                final ServletContext ctx = (ServletContext) obj;
                final BeanManager tmp = (BeanManager) ctx
                    .getAttribute("org.ops4j.pax.cdi.BeanManager");
                if (tmp == null) {
                    return null;
                }
                this.beanManager = tmp;
                return beanManager;
            }
            else {
                notFound = true;
            }
        }
        catch (Exception t) {
            throw new IllegalStateException("Exception fetching BeanManager instance!", t);
        }
        if (notFound) {
            throw new IllegalStateException("Not in a servlet or portlet environment!");
        }
        return null;
    }
}